generic_stages: Add build important/experimental as stage metric field.

BUG=chromium:635958
TEST=./run_tests

Change-Id: Id6800ee4f8e2655b35bc46a55a48e9688c4cd1b7
Previous-Reviewed-on: https://chromium-review.googlesource.com/383954
(cherry picked from commit 1b662bf1aacba8eab00bf15f705bd90c3a8faacb)
Reviewed-on: https://chromium-review.googlesource.com/407878
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
Commit-Queue: Aviv Keshet <akeshet@chromium.org>
Tested-by: Aviv Keshet <akeshet@chromium.org>
1 file changed